Abnormal openings, holes or shunts can occur between the chambers of the heart or the great vessels, causing shunting of blood through the opening or the passage. Such abnormal openings can for example occur as ventricular septal defects, atrial septal defects and patent ductus arteriosus. In order to avoid morbidity and mortality associated with open-heart surgery a variety of transcatheter closure techniques have been attempted. In these techniques an occluding device is delivered through a catheter. Once the occluding device is positioned adjacent the defect, it must be attached to the rest of the septum in a manner which permits it to effectively block the passage of blood through the defect.
U.S. Pat. No. 4,836,204 describes an occluder consisting of two inflatable balloons made of latex or rubber. The two balloons are spaced from each other by a shaft of a catheter. The balloons are inflated and they close the passage in their inflated shape. This occluder needs quite a lot of space and can therefore not be used for closing small openings.
WO 97/41779 discloses an occluding device comprising a fluid tight inflatable double chamber balloon. A connection part between the two chambers is arranged to form guidance for the two chambers around a peripheral edge of the passage to be closed. Both chambers can be dilated radially by a number of stiffening means. These stiffening means are in a first embodiment metallic coils springs arranged in the chambers and in a second embodiment metallic threads. A locking mechanism comprising two snap together members arranged at each end of the balloon is provided for fixing the balloon in its dilated and evacuated position or for locking the threads in a twisted spring-like position. Metallic parts can however have a negative impact in view of cardiac arrhythmias.
FR 2 714 284 describes an occluder with a double chamber balloon, the balloon being made of a material with shape memory properties. The distal end of the balloon is closed and the proximal end comprises a valve. The balloon is inflated and placed at the location of the defect. It is then evacuated. The catheter is left in place for a certain period of time to make sure that the balloon remains at the chosen location.
The occluders according to the state of the art have the disadvantage that they are complicated in their construction and therefore also quite complicated to handle. In particular, when they are at the location of the defect, their final location and their shape can hardly be manipulated or affected.
U.S. Pat. No. 6,692,494 discloses a device to produce and maintain collateral openings or channels through an airway wall so that expired air is able to pass directly out of the lung tissue to facilitate both the exchange of oxygen into the blood and/or to decompress hyper-inflated lungs. The device can be delivered using an hour glass shaped balloon catheter. This balloon is removed after the device is delivered.